ALK-Positive Large B Cell Lymphoma—Unusual Subtype of Diffuse Large B Cell Lymphoma (DLBCL)

Anaplastic lymphoma kinase positive diffuse large B-cell lymphoma (ALK-DLBCL) is a rare lymphoma and has been included as a separate entity in the latest WHO classification (2008) of Non-Hodgkin’s lymphomas. We report a case of 65-year-old male patient who presented with multiple subcutaneous nodules on abdominal wall. Histomorphology and Immunohistochemical profile was consistent with that of ALK-positive diffuse large B cell Lymphoma. Anaplastic lymphoma kinase (ALK) staining was cytoplasmic granular staining pattern highly indicative of expression of Clathrin gene (CLTC-ALK protein). CD 20 was strongly expressed in this case which was an unusual finding as this has been reported in only a few cases which have been published. Our patient also responded well to rituximab therapy which is not administered as these are usually CD 20 negative. The case is reported for its rarity and to make the clinicians aware of this entity so that these cases may be diagnosed early and treated aggressively.